9 research outputs found
Catalytic oxidation of organic sulfides by H2O2 in the presence of titanosilicate zeolites
[EN] Titanosilicate ferrierite zeolite (FER) and its delaminated form (ITQ-6), with various Si/Ti molar ratios, were synthetized and tested as catalysts for diphenyl sulfide (Ph2S) and dimethyl sulfide (DMS) oxidation with H2O2. The zeolites were characterized with respect to their chemical composition (ICP-OES), structure (XRD, UV-vis DRS) and texture (low-temperature N-2 adsorption-desorption). Titanium in the FER and ITQ-6 samples was present mainly in the zeolite framework with a significant contribution of titanium in the extraframework positions. Titanosilicate zeolites of FER and ITQ-6 series were found to be active catalysts of diphenyl and dimethyl sulfides oxidation by H2O2 to sulfoxides (Ph2SO/DMSO) and sulfones (Ph2SO2/DMSO2). The efficiency of these reactions depends on the porous structure of the zeolite catalysts - conversion of larger molecules of diphenyl sulfide was significantly higher in the presence of delaminated zeolite Ti-ITQ-6 due to the possibility of the interlayer mesopores penetration by reactants. On the other side diphenyl sulfide molecules are too large to be accommodated into micropores of FER zeolite. The efficiency of dimethyl sulfide conversion, due to relatively small size of this molecule, was similar in the presence of Ti-FER and Ti-ITQ-6 zeolites. For all catalysts, the organic sulfide conversion was significantly intensified under UV irradiation. It was suggested that Ti cations in the zeolite framework, as well as in the extraframework, species play a role of the single site photocatalysts active in the formation of hydroxyl radicals, which are known to be effective oxidants of the organic sulfides.The studies were carried out in the frame of project 2016/21/B/ST5/00242 from the National Science Centre (Poland). Part of the research was done with equipment purchased in the frame of European Regional Development Fund (Polish Innovation Economy Operational Program -contract no. POIG.02.01.00-12-023/08). U.D. acknowledges to the Spanish Government by the funding (MAT2017-82288-C2-1-P). The work was partially supported by the Foundation for Polish Science (FNP) within the TEAM project (POIR.04.04.00-00-3D74/16).Radko, M.; Rutkowska, M.; Kowalczyk, A.; Mikrut, P.; Swies, A.; Díaz Morales, UM.; Palomares Gimeno, AE.... (2020). Catalytic oxidation of organic sulfides by H2O2 in the presence of titanosilicate zeolites. 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Titanium dioxide doped with vanadium as effective catalyst for selective oxidation of diphenyl sulfide to diphenyl sulfonate
Inhibition of the enzyme urease pollutants in the context of soil enzyme activities. chromium compounds. UV-vis spectroscopy.
Badano wpływ związków chromu(VI) i (III) na enzym ureazę metodą spektroskopii UV-vis. Sporządzono roztwory K2CrO4 o pH = 7,4; K2Cr2O7 o pH = 6,4 i CrCl3 o pH = 6,4 oraz roztwory ureazy, wszystkie w 200 mM buforze HEPES w odpowiednim pH. Zarejestrowano widma UV-vis czystych roztworów związków chromu oraz ureazy, a następnie mieszaniny inkubacyjnej Cr-ureaza. Dla danej mieszaniny, widma rejestrowano w 10 minutowych odstępach czasowych do 80 min inkubacji. Zaobserwowano, że przesunięcia maksimów absorpcji mieszaniny inkubacyjnej Cr-ureaza w stosunku do maksimum samej ureazy są niewielkie (1-2 nm). Podobne obserwacje podaje praca Zhang i wsp. (Biol. Trace Elem. Res., 141, 53-64, 2011), gdzie wyniki zinterpretowano jako dowód zmian strukturalnych w ureazie. Naszym zdaniem przesunięcia te należy sklasyfikować jako błąd pomiarowy.The effect of chromium(VI) and (III) compounds on the enzyme urease was studied with UV-vis spectroscopy. Solutions of K2CrO4 at pH 7,4; K2Cr2O7 at pH 6,4 and of CrCl3 at pH 6,4 as well as the solutions of urease were prepared in 200 mM HEPES buffer at respective pHs. The UV-vis spectra were recorded for pure solutions of chromium compounds and for urease, and then for the Cr-urease incubation mixture. For a given mixture, the spectra were recorded at 10 minute intervals up to 80 min incubation. It was observed that the shift of the maximum absorption of the Cr-urease incubation mixture relative to urease alone was small (1-2 nm). Similar observations were reported Zhang i wsp. (Biol. Trace Elem. Res., 141, 53-64, 2011), where they were interpreted as evidence for structural changes in urease. In our opinion, the shifts should be regarded as those within the experimental error
Synthesis of hybrid organic-inorganic adsorbents for environmental process.
Celem niniejszej pracy było uzyskanie hybrydowych organiczno-nieorganicznych adsorbentów, które mogą być wykorzystane w wielu różnych procesach środowiskowych. Materiały hybrydowe mają wiele zalet: wysoką selektywność adsorpcji w wiązaniu organicznych lub nieorganicznych zanieczyszczeń, szybkość wychwytu zanieczyszczeń i regeneracji. Jednym z aspektów pracy była synteza mezoporowatej, uporządkowanej krzemionki z heksagonalnym ułożeniem cylindrycznych porów – SBA-15. Krzemionka została zmodyfikowana przez czynniki spęczniające: alkohol lub mieszaninę heptan/fluorek amonowy. Synteza krzemionki o większych porach umożliwia wiązanie grup organofunkcyjnych z większymi cząstkami zanieczyszczeń i dostęp do każdego centrum wiążącego na powierzchni. W następnym etapie syntezy przeprowadzono szczepienie z homogenicznym procesem łączenia reagentów organosilanowych na powierzchni materiału. 3-chloropropylotrimetylosilan lub 3-isocyjanopropylotrietylosilanpołączono z odpowiednią grupą funkcyjną i graftowano na powierzchni krzemionki wewnątrz porów. Grupy organosilanofunkcyjne udało się wprowadzić do materiału SBA-15. Skuteczność procesu szczepienia została potwierdzona analizą chemiczną i IR. Ponadto wykazano, że nie następuje znacząca utrata powierzchni właściwej i objętości porówThe aim of the presented work was to obtain hybrid organic-inorganic adsorbents which can be used in many different environmental processes. Hybrid materials have many adsorption advantages: high selectivity of binding organic or inorganic pollutant moieties, rate of uptake pollutants and regeneration. One aspect of the study was synthesis of mesoporous, ordered silica with hexagonal arrangement of cylindrical pores- SBA-15. Silica was modified by swelling agents: alcohol or mixture of heptane/ ammonium fluoride. Preparation of silica with larger pores allows binding organofunctional groups with larger pollutant moieties and access to each binding center on the surface. In the next step, post synthesis grafting with homogenous process of connecting organosilane reagents on the material surface was performed. 3-chloropropyltrimethosysilane or 3-isocyanatopropylotriethosysilane with suitable functional group, inside mesopores, were connected to the silica surface. Organofunctional groups were successfully introduced to an SBA-15 material. Efficiency of grafting process was confirmed by chemical analysis and IR. Additionally it was shown that no significant loss of surface area and pore volume occurred
Interaction between adsorbed molecules and tailor made large chelating ligands grafted on SBA-15 studied by means of thermoporometry
Modified mesoporous silicas were examined as adsorbents for efficient removal of model pollutants from wastewaters. Functionalized SBA-15 materials for capture of cationic pollutants such as metal cations and anionic dyes were obtained using post-synthesis grafting method. Large organic ligands containing acetyloacetone, 2-aminopyridine, 2-aminothiazole and 2-aminobenzothiazole groups were incorporated into the adsorbents' structure. The adsorption capacities reached levels of 38.6, 43.1, 64.3, 68.6 and 88.9 mg g−1 for Cu2+, Rose Bengal, Congo Red, Levafix Amber CA gran and Methyl Orange, respectively. Moreover, the adsorption efficiency depended on a type of the model molecule and a type of the surface chelating group. The pores' size and the pores' volume of the hybrid materials before and after adsorption was determined in hydrated state using thermoporometry. For the first time, by means of this methodology, it was possible to propose a model of interactions between the adsorbed molecules and the grafted organosilanes. Adsorption of organic dyes resulted in most cases in formation of J-aggregates.Part of the research was carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract no. POIG.02.01.00-12-023/08) and within the scope of the project of Labóratorio Associado para Química Verde – Technologia e Processos Limpos – UID/QUI/50006, is financed by national founds of FCT/MEC and co-financed by Fundos FEDER (POCI-01-0145-FEDER-007265) within the scope of the partnership agreement PT2020. To all financing sources the authors are greatly indebted.info:eu-repo/semantics/publishedVersio
Catalytic and photocatalytic oxidation of diphenyl sulphide to diphenyl sulfoxide over titanium dioxide doped with vanadium, zinc, and tin
Samples of TiO(2) (P25) doped with zinc, tin, and vanadium, thermally treated at 550 °C for 6 h, were tested as catalysts and photocatalysts for the oxidation of diphenyl sulphide to diphenyl sulfoxide and sulfone, using hydrogen peroxide as an oxidation agent. Thermal treatment of pure TiO(2) and its vanadium-doped forms resulted in a decrease of anatase and an increase of rutile content. The opposite effect was observed for TiO(2) doped with zinc or tin, where thermal treatment resulted in the rutile to anatase phase transition. The role of V, Zn, and Sn admixtures as TiO(2) phase-composition controllers was postulated. The catalytic and photocatalytic activity was found to be influenced more by the rutile and anatase contents of the samples than the presence of admixtures. The rutile-containing samples, TiO(2) and V-TiO(2), presented much better activity in the catalytic oxidation of diphenyl sulphide compared with the catalysts that only contained the anatase phase, Sn-TiO(2) and Zn-TiO(2). The reaction efficiency was significantly improved under UV radiation. In this case, the best photocatalytic activity was found for calcined TiO(2), containing both anatase and rutile components. An increase in rutile content, observed in the vanadium-doped TiO(2), decreased the efficiency of the photocatalytic diphenyl sulphide oxidation. Thus, the presence of both anatase and rutile phases, with their favourable contributions, typical for P25, is necessary for the effective oxidation of Ph(2)S to Ph(2)SO. Moreover, it was shown that for the second oxidation stage, Ph(2)SO to Ph(2)SO(2), the presence of the rutile phase is very important